Validate and format phone numbers - retain country codes and extensions

validateFormatPhone.php

<?php
function formatPhone($num) {
    $num = preg_replace('/[^\dx]/i', '', $num);
	preg_match('/(x)\.?:?\s*?(\d+)/i', $num, $ext);

	if (!empty($ext)) {
	    $ext = ' ext ' . preg_replace('/\D/', '', $ext[0]);
	    $num = preg_replace('/(x)\.?:?\s*?(\d+)/i', '', $num);
	}
	
	$number = preg_replace('/\D/', '', $num);
	$length = strlen($number);

	if ($length == 7) {
		$r = preg_replace("/(\d{3})(\d{4})/", "$1-$2", $number);
	} else if ($length == 10) {
		$r = preg_replace('/^1?(\d{3})(\d{3})(\d{4})$/', "$1-$2-$3", $number);
	} else if ($length > 10 && $length < 13) {
		$r = preg_replace('/^1?(\d{1,2})(\d{3})(\d{3})(\d{4})$/', "+$1 $2-$3-$4", $number);
	} else if ($length == 13) {
		$r = preg_replace('/^(\+\s*)?(\d{1,2})(\d{1})(\d{3})(\d{3})(\d{4})$/', "$1 $2-$3-$4-$5", $number);
	} else {
	    $r = $number . ' - INVALID NUMBER';
	}
	
	# apply the extension if available
	if (!empty($ext)) {
	    $r = $r . $ext;
	}
	
	return $r;
}

$numbers = array(
	'-234-567-8901',
	'1-234-567-8901',
	'1-234-567-8901 x1234',
	'1-234-567-8901 ext1234',
	'1 (234) 567-8901',
	'1.234.567.8901',
	'1/234/567/8901',
	'12345678901',
	'(+351) 282 43 50 50',
	'90191919908',
	'555-8909',
	'001 6867684',
	'001 6867684x1',
	'1 (234) 567-8901',
	'1-234-567-8901 x1234',
	'1-234-567-8901 ext1234',
	'1-234 567.89/01 ext.1234',
	'1(234)5678901x1234',
	'(123)8575973',
	'(0055)(123)8575973',
	'(123)456-7890',
	'(123)-456-7890',
	'(123) 456-7890',
	'(123) 456-7890 x123',
	'12 1234 123 1 x1111',
	'12 12 12 12 12',
	'12 1 1234 123456 x12345',
	'+12 1234 1234',
	'+12 12 12 1234',
	'+12 1234 5678',
	'+12 12345678',
	'(123)456789',
	'(123456789',
	'(123 456 789',
	'(123.456.789',
	'(123-456-789',
	'123)456789',
	'123) 456 789',
	'123).456.789',
	'123)-456-789',
);

foreach ($numbers as $phone) {
	echo $phone . ': ' . "\t\t" . formatPhone($phone) . PHP_EOL;
}